My External hard disk is not opening. At first, it seeks a format. But, after trying to format it says, windows failed to format.

The error at the event viewer is as follows:
err1: The device, \Device\Harddisk2\DR2, has a bad block
err2: The driver detected a controller error on \Device\Harddisk2\DR2.

After googling with the problem, I found a suggestion to apply the command "chkdsk x: /f". While running the "chkdsk" command, at the 3 of 3 stage (CHKDSK is verifying the security descriptors) it shows one line consecutively and that is
"Correcting errors in the volume Bitmap" -
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"Correcting errors in the volume Bitmap"